Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters

<p>Abstract</p> <p>Background</p> <p>Human metapneumovirus (hMPV) infection can cause acute lower respiratory tract illness in infants, the immunocompromised, and the elderly. Currently there are no licensed preventative measures for hMPV infections. Using a variant of hMPV/NL/1/00 that does not require trypsin supplementation for growth in tissue culture, we deleted the M2-2 gene and evaluated the replication of rhMPV/ΔM2-2 virus <it>in vitro </it>and <it>in vivo</it>.</p> <p>Results</p> <p><it>In vitro </it>studies showed that the ablation of M2-2 increased the propensity for insertion of U nucleotides in poly-U tracts of the genomic RNA. In addition, viral transcription was up-regulated although the level of genomic RNA remained comparable to rhMPV. Thus, deletion of M2-2 alters the ratio between hMPV genome copies and transcripts. <it>In vivo</it>, rhMPV/ΔM2-2 was attenuated compared to rhMPV in the lungs and nasal turbinates of hamsters. Hamsters immunized with one dose of rhMPV/ΔM2-2 were protected from challenge with 10⁶PFU of wild type (<it>wt) </it>hMPV/NL/1/00.</p> <p>Conclusion</p> <p>Our results suggest that hMPV M2-2 alters regulation of transcription and influences the fidelity of the polymerase complex during viral genome replication. In the hamster model, rhMPVΔM2-2 is attenuated and protective suggesting that deletion of M2-2 may result in a potential live vaccine candidate. A more thorough knowledge of the hMPV polymerase complex and the role of M2-2 during hMPV replication are being studied as we develop a potential live hMPV vaccine candidate that lacks M2-2 expression.</p

Pediatric endurance and limb strengthening for children with cerebral palsy (PEDALS) – a randomized controlled trial protocol for a stationary cycling intervention

BACKGROUND: In the past, effortful exercises were considered inappropriate for children with spastic cerebral palsy (CP) due to concern that they would escalate abnormalities including spasticity and abnormal movement patterns. Current scientific evidence indicates that these concerns were unfounded and that therapeutic interventions focused on muscle strengthening can lead to improved functional ability. However, few studies have examined the potential benefits of cardiorespiratory fitness exercises in this patient population. METHODS/DESIGN: The rationale and design of a randomized controlled trial examining the effects of a stationary cycling intervention for children with CP are outlined here. Sixty children with spastic diplegic CP between the ages of 7 and 18 years and Gross Motor Function Classification System (GMFCS) levels of I, II, or III will be recruited for this study. Participants will be randomly assigned to either an intervention (cycling) or a control (no cycling) group. The cycling intervention will be divided into strengthening and cardiorespiratory endurance exercise phases. During the strengthening phase, the resistance to lower extremity cycling will be progressively increased using a uniquely designed limb-loaded mechanism. The cardiorespiratory endurance phase will focus on increasing the intensity and duration of cycling. Children will be encouraged to exercise within a target heart rate (HR) range (70 – 80% maximum HR). Thirty sessions will take place over a 10–12 week period. All children will be evaluated before (baseline) and after (follow-up) the intervention period. Primary outcome measures are: knee joint extensor and flexor moments, or torque; the Gross Motor Function Measure (GMFM); the 600 Yard Walk-Run test and the Thirty-Second Walk test (30 sec WT). DISCUSSION: This paper presents the rationale, design and protocol for Pediatric Endurance and Limb Strengthening (PEDALS); a Phase I randomized controlled trial evaluating the efficacy of a stationary cycling intervention for children with spastic diplegic cerebral palsy

A Single Amino Acid Substitution in the Viral Polymerase Creates a Temperature-Sensitive and Attenuated Recombinant Bovine Parainfluenza Virus Type 3

AbstractBovine parainfluenza virus type 3 (bPIV3) is under development as a live virus vaccine vector. The RNA genome of a recombinant bPIV3 harbored four nucleotide changes, one of which resulted in a mutation of the viral polymerase (A. A. Haller et al., 2000, J. Virol. 74, 11626–11635). The contribution of this conservative amino acid substitution (I1103V) in the polymerase to the temperature-sensitive and attenuation phenotypes of r-bPIV3 was investigated by creating a new virus, r-bPIV3(I), that expressed the wild-type polymerase. r-bPIV3(I) was not temperature-sensitive for growth in vitro and the replication of r-bPIV3(I) was no longer restricted in hamsters. The effect of the amino acid substitution in the polymerase was also studied in a chimeric bovine/human PIV3, a virus that displayed temperature-sensitive and attenuated phenotypes (A. A. Haller et al., 2000, J. Virol. 74, 11626–11635). It was not clear whether these defects were due to the impaired polymerase or the replacement of the bPIV3 surface glycoproteins with those of hPIV3. The results showed that the altered polymerase was indeed responsible for the temperature-sensitive phenotype of bovine/human PIV3 but did not appear to play a role in the attenuation phenotype

Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters-5

D to introduce the SwaI site are underlined. Translational stop codons are bold and the intergenic (IG) sequence is bold italics. B) To construct rhMPV/GFPpolyA, an NheI site was introduced at the M2-2 stop codon of rhMPV and an NheI-N/P-GFP-polyA-NheI cassette was inserted. The modified nucleotides are underlined, the stop codon is bold and the IG sequence is bold italics. C) To construct rhMPV/ΔM2-2/GFPpolyA, an NheI site was introduced between the stop codon of M2-1 (bold) and the SwaI site (italics) in rhMPV/ΔM2-2 and an NheI-N/P-GFP-polyA-NheI cassette was inserted. The modified nucleotides are underlined and the IG sequence is in bold italics. D) The reading frame of GFP is aligned with that of GFPpolyA to show the stop codon and frame shift resulting from the 11 nt insertion.<p><b>Copyright information:</b></p><p>Taken from "Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters"</p><p>http://www.virologyj.com/content/5/1/69</p><p>Virology Journal 2008;5():69-69.</p><p>Published online 3 Jun 2008</p><p>PMCID:PMC2426676.</p><p></p

Parainfluenza Virus Type 3 Expressing the Native or Soluble Fusion (F) Protein of Respiratory Syncytial Virus (RSV) Confers Protection from RSV Infection in African Green Monkeys

Respiratory syncytial virus (RSV) causes respiratory disease in young children, the elderly, and immunocompromised individuals, often resulting in hospitalization and/or death. After more than 40 years of research, a Food and Drug Administration-approved vaccine for RSV is still not available. In this study, a chimeric bovine/human (b/h) parainfluenza virus type 3 (PIV3) expressing the human PIV3 (hPIV3) fusion (F) and hemagglutinin-neuraminidase (HN) proteins from an otherwise bovine PIV3 (bPIV3) genome was employed as a vector for RSV antigen expression with the aim of generating novel RSV vaccines. b/h PIV3 vaccine candidates expressing native or soluble RSV F proteins were evaluated for efficacy and immunogenicity in a nonhuman primate model. b/h PIV3 is suited for development of pediatric vaccines since bPIV3 had already been evaluated in clinical studies in 1- and 2-month-old infants and was found to be safe, immunogenic, and nontransmissible in a day care setting (Karron et al., Pediatr. Infect. Dis. J. 15:650-654, 1996; Lee et al., J. Infect. Dis. 184:909-913, 2001). African green monkeys immunized with b/h PIV3 expressing either the native or soluble RSV F protein were protected from challenge with wild-type RSV and produced RSV neutralizing and RSV F-protein specific immunoglobulin G serum antibodies. The PIV3-vectored RSV vaccines evaluated here further underscore the utility of this vector system for developing safe and immunogenic pediatric respiratory virus vaccines

Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters-2

5 in NCR of SH, contained this sequence showing two subpopulations. One population is the correctly cloned sequence; the second population has one inserted A nt (sense direction) at nt5222 in the M2-1 gene. B) To assess the relative frequency of mutations, RT-PCR fragments spanning nt4536 in F to nt5623 in SH were obtained from rhMPV/ΔM2-2 or rhMPV using one-step RT-PCR, and were cloned into pCR2.1 plasmids. Among 15 independent plasmids the number of inserted As, single nt deletions, and point mutations (transition or transversion) for each virus were tabulated. 14 of the 15 (93%) rhMPV/ΔM2-2RT-PCR products had an inserted A (sense direction) nucleotide. No fragments containing A nucleotide insertions were detected in any of the 15 RT-PCR fragments spanning the identical region in P4 of rhMPV. C) To study frequency of mutations in genomic RNA, RT-PCR fragments spanning nt4536 to nt5623 were obtained from rhMPV/ΔM2-2 using two-step RT-PCR, and were cloned into pCR2.1 plasmids. Nucleotide insertions were predominantly T (genomic antisense direction), with one A, and were distributed among 8 locations in the fragments. D) To describe the position where insertion of an A was observed, the nt number of the last A in the poly A tract is used, though it is not known which A residue in the poly A tract is the inserted residue. The example shown is A inserted at nt5166.<p><b>Copyright information:</b></p><p>Taken from "Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters"</p><p>http://www.virologyj.com/content/5/1/69</p><p>Virology Journal 2008;5():69-69.</p><p>Published online 3 Jun 2008</p><p>PMCID:PMC2426676.</p><p></p

Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters-4

S and supernatants were harvested daily. Total RNA was extracted, and 7 replicate aliquots were separated on 1% agarose gel in the presence of 0.44 M formaldehyde gel, transferred to a nylon membrane and hybridized with digoxigenin-labeled single-stranded anti-sense riboprobes to detect mRNA as follows: A) M2 riboprobe; B) SH riboprobe; C) N riboprobe; D) F riboprobe; E) G riboprobe. F) Sense P, M, and F riboprobes were combined to detect genomic RNA. G) RNA in a duplicate gel was visualized with ethidium bromide and photographed under UV light. H) Titers of samples prior to RNA extraction were determined by plaque assay in Vero cells.<p><b>Copyright information:</b></p><p>Taken from "Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters"</p><p>http://www.virologyj.com/content/5/1/69</p><p>Virology Journal 2008;5():69-69.</p><p>Published online 3 Jun 2008</p><p>PMCID:PMC2426676.</p><p></p

Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters-6

Hylcellulose in optiMEM. At 6 days p.i., the cells were fixed in methanol and immunostained with ferret polyclonal antibody directed to hMPV followed by anti-ferret horse radish peroxidase-conjugated antibody. The immunostained plaques were treated with 3-amino-9-ethylcarbazole for visualization. B) Replicate cultures of Vero cells were inoculated with rhMPV or rhMPV/ΔM2-2 at MOI of 0.1 PFU/cell and incubated at 35°C. Supernatants and cells were harvested daily for 4 days. Titers were determined by plaque assay in Vero cells. The graph represents an average +/- SD titer of three independently performed experiments.<p><b>Copyright information:</b></p><p>Taken from "Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters"</p><p>http://www.virologyj.com/content/5/1/69</p><p>Virology Journal 2008;5():69-69.</p><p>Published online 3 Jun 2008</p><p>PMCID:PMC2426676.</p><p></p

Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters-1

Hylcellulose in optiMEM. At 6 days p.i., the cells were fixed in methanol and immunostained with ferret polyclonal antibody directed to hMPV followed by anti-ferret horse radish peroxidase-conjugated antibody. The immunostained plaques were treated with 3-amino-9-ethylcarbazole for visualization. B) Replicate cultures of Vero cells were inoculated with rhMPV or rhMPV/ΔM2-2 at MOI of 0.1 PFU/cell and incubated at 35°C. Supernatants and cells were harvested daily for 4 days. Titers were determined by plaque assay in Vero cells. The graph represents an average +/- SD titer of three independently performed experiments.<p><b>Copyright information:</b></p><p>Taken from "Deletion of human metapneumovirus M2-2 increases mutation frequency and attenuates growth in hamsters"</p><p>http://www.virologyj.com/content/5/1/69</p><p>Virology Journal 2008;5():69-69.</p><p>Published online 3 Jun 2008</p><p>PMCID:PMC2426676.</p><p></p